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JavaScript AJAX

AJAX (Asynchronous JavaScript and XML) is a technique for creating fast and dynamic web pages that allow for real-time updating without reloading the entire page.

It is a combination of multiple technologies, including HTML, CSS, JavaScript, and XML (or JSON).

Here's a basic example of how AJAX works:

function loadXMLDoc() {
  const xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function () {
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("demo").innerHTML = this.responseText;
    }
  };
  xhttp.open("GET", "ajax_info.txt", true);
  xhttp.send();
}

In this example

  • The loadXMLDoc() function creates a new XMLHttpRequest object and defines a callback function that is executed when the state of the request changes.
  • The xhttp.open() method sets the HTTP request method, the URL of the file to be requested, and a boolean value that specifies whether the request should be asynchronous or not.
  • The xhttp.send() method sends the request to the server.
  • When the server responds, the callback function is executed, and the response text is displayed in an HTML element with the ID "demo".

Importance of AJAX​

Here are some key points highlighting the importance of AJAX:

Improved user experience​

AJAX allows for dynamic updates to web pages without the need for a full page reload, resulting in a more seamless and responsive user experience.

Reduced server load​

By sending and receiving data in the background, AJAX requests can reduce the server load and network traffic, resulting in faster and more efficient web applications.

Better performance​

AJAX can be used to load data asynchronously, allowing for faster page rendering and improving overall performance.

Interactive web applications​

AJAX enables developers to create more interactive web applications that can respond to user input and update the UI dynamically, resulting in a more engaging user experience.

Platform independence​

AJAX is a cross-platform technology that can be used across multiple browsers and operating systems, making it a versatile solution for creating modern web applications.

tip

Try to use the fetch() API in modern browsers instead of traditional AJAX requests using XMLHttpRequest